Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-06-18
2001-07-03
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Attachment
C280S741000, C180S271000
Reexamination Certificate
active
06254124
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method for operating a vehicle occupant restraint system.
Furthermore, the invention relates to a device for carrying out the method according to the invention.
BACKGROUND OF THE TNVENTION
Multiple-stage gas generators with propellant charges which are able to be ignited independently of each other can generate different quantities of gas, coordinated with vehicle occupants or accident-specific parameters. If not all the propellant charges are ignited to achieve the optimum restraining effect, but only some of them, the outflowing hot gas, however, automatically heats the outer and inner walls, so that heat is passed on to the at least one non-ignited charge. Theoretically, this can lead to the self ignition of the non-ignited charge after a few minutes, due to the relatively slow transportation of heat. This involves dangers both for the occupant still situated in the vehicle, and also for rescue personnel.
Furthermore, a gas generator in which not all the stages are ignited represents a problem with regard to recycling/disposal. Generally it is not—at least not simply—possible to detect from the exterior, whether all the stages have been ignited, so that a recycling or a disposal of an activated gas generator will take an increased effort in terms of safety.
BRIEF SUMMARY OF THE INVENTION
The invention provides a method in which the above-mentioned dangers and problems can be largely ruled out. This is achieved according to the invention by a method for operating a vehicle occupant restraint system, with a gas bag, which has a range of action which is defined by its occupied space in an inflated state of the gas bag, and a multiple-stage gas generator, which has several individually ignitable propellant charges. In the case of an accident, in which not all the stages are ignited to achieve a desired restraining effect, the non-ignited stage/stages is/are ignited at such a moment when it/they substantially can no longer have a restraining effect on the occupant.
The invention accordingly makes provision that in any case the stages which are not yet ignited are activated, so that always all the charges will be ignited or all stages activated even if not all stages are to be activated, in order to obtain the desired restraining effect tailored with respect to the conditions of the crash. The ignition of the non-activated stages takes place, however, when these cannot represent any further danger to the occupant, i.e. when no or substantially no further restraining effect can be achieved by them.
Preferably the activation of the non-ignited stages takes place when the occupant is situated outside the range of action or substantially outside, i.e. at the outer portions of the gas bag. However, as very small occupants under certain circumstances sit very close to the restraint system, theoretically it can occur that for example a driver's gas bag in its inflated state touches the occupant even if the occupant has leant back completely. In this position of the occupant, a restraining effect can still be exerted by the gas bag, which, however, is not as large as in the case of an occupant with his upper body moved forward. For this reason it was previously defined that the activation of the stages which were not yet ignited is to take place when substantially no further restraining effect can be exerted on the occupant. Thus, it is possible to predetermine a certain risk of being injured (e.g. by predetermining a minimum distance of the head to the steering wheel or a point of time when the occupant is moving backwardly), wherein the non-ignited steps are activated upon falling below the predetermined risk. Preferably, however, the vehicle occupant restraint system is to be constructed and the method is to be operated such that on ignition of the not yet activated stages no restraining effect at all can be exerted on the occupant.
The invention further provides a device for carrying out the method according to the invention. The device comprises a gas bag, a multiple-stage gas generator which has several individually ignitable propellant charges, and a control unit, which controls the activation of the propellant charges.
According to a preferred embodiment, provision is made that the ignition of the ncn-ignited stage/stages takes place when the occupant, after having dived into the gas bag, is in a rearward movement, also known as rebound. The activation of the non-ignited stage/stages can take place after a predetermined time, e.g. between 80 and 150 ms, after the ignition of the stage/stages necessary to achieve the restraining effect. In about this time range the rearward displacement of the occupant takes place so that the gas bag, which is again inflated by the lately activated stage(s), does not act as restraint means.
Furthermore, the activation of the not yet ignited stages can also take place as a function of the actual position of the occupant, not only the assumed position. This is achieved by at least one sensor. This sensor detects when the occupant is again situated outside or almost outside the range of action of the gas bag after having dived into the gas bag. A control unit which is connected with the sensor activates the non-ignited stage/stages in response to a corresponding signal of the sensor.
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Dickson Paul N.
Draper Deanna
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Airbag Systems GmbH & Co. KG
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